Motor-generator set and generator



J 1942- J. H. BLANKENBUEHLER 7, 9

MOTOR'GENERA'IOR SET AND GENERATOR 2 sheets-sheet .1.

Filed June 23, 1939 hm ow WlTNESSES: INVENTOR JohhiH Blafilce bueblez" .1 AM

Patented June 30, 1942 MOTOR-GENERATOR SET AND GENERANB John H. Blankenbuehler, Edgewood, 2a., asaignor to Westinghouse Electric 8; Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 23, 1939, Serial No. 280,887

6 Claims. 171-123) 'and economical in operation.

An important object of my invention is to provide in a simple and effective manner for con trolling the output of a cross-field welding generator over a wide range of current values.

' Another object of my invention is to provide for controlling the output of a cross-field generator by utilizing a slidable magnetic shunt member positioned in bridged relation with the field poles of the generator.

Still another object of my invention is to provide for controlling the output, of a, crossfield welding generator by eilecting movement of a magnetic shunt member, which bridges the adjacent portions of the' field pole members, along a predetermined path in response to actuation of the member in a given direction.

Another important object of my invention is to provide in a simple and eflfective manner for regulating the output of a welding generator of the cross-field type, so as to secure a wide range of output control without requiring a complicated operating mechanism.

A further object of my invention is to provide in a simple and eflective manner for mounting the motor and generator controls of a motorgenerator welding power unit in associated rela tion on an end member of the unit behind a pro tective cover which blends with the outline of the unit.

Other objects will, in part, be obvious, and

will, in part, appear hereinafter.

In one embodiment of my invention, the motor-generator power unit comprises a common elongated tubular frame formed oi a length of pipe, or the like, having a motor stator structure mounted therein adjacent one end, a field structure for a generator, which is preferably of the cross-field type, positioned therein adjacent the other end, and a rotor member comprising a motor rotor and a generator armature positioned in rotatable relation thereto. A magnetic shunt member is positioned between the adjacent shoe portions of the opposing field pole members of the generator field structure and actuated by means of a traveling nut indicator member on an axially disposed threaded rod which may extend from the generator end of the frame and be provided with operating means such as a handwheei. The movement of the shunt'member relative to the shoe portions is preferably controlled by means of guide members which support the shunt member on bearing surfaces which may have any desired slope, or contour, so as to eii'ect a predetermined movement of the shunt member with respect to the pole shoes in response to operation of the actuating means.

The common frame may be provided with an end member at the generator end which not only supports one end of the rotor member of the machine but which also serves as a mounting for switches of various kinds, such, for example, as a control switch for controlling the terminal polarity of the generator, and a line switch for controlling the energization of the motor. By thus positioning these control devices they are not only adjacent the output control handwheel of the generator, but theyare also made as free from vibration as possible, and readily accessible, and may be protected and concealed by a metal end cover harmonizing with the outlines of the unit.

For a more complete understanding of the nature and scope of my invention, reference may be made to the Iollowing detailed description,

taken in connection with the accompanyingdrawings, in which:

Figure l is a longitudinal section view of a motor-generator unit embodying one form of my invention;

Fig. 2 is a cross-section view of the unit of Fig. 1 along the line II-II showing details of the generator construction;

Fig. 3 is an end elevation iew of the motorgenerator unit 0! Fig. 1 from the generator end with the protective end cover removed;

Fig. 4 is a side elevational view of the generator end member with the protective cover sectioned, showing details of the mounting of the motor and generator switches;

Fig. 5 is a diagrammatic view of the magnetic circuits of the generator showing the main flux paths under load conditions;

Fig. 6 is a diagrammatic view showing the flux distribution in the generator when the load is removed;

Fig. 7 is an enlarged plan view of the magnetic shunt member;

Fig. 8 is an enlarged end view of the magnetic shunt member of Fig. 7;

Figs. 9 and 10 are enlarged side elevation views end member 26 end of the tubular frame II by suitable means.

- 'erator'md positioning the 23 structure are disclosed cation of John H. Blankenbuehler and William "for example, iron, or the like, having a relatively small crossof the bers;

Fig. 11 is a schematic diagram showing the circuit connections of the motor-generator unit guide members mounted on the shoe memof Fig. 1, and

a generator field structure l3, comprising oppo sitely positioned neld'pole members i4 and i5,

with field windings l3 and i1 disposed thereon,

. positioned therein at the other end. A common rotor member i3 comprising a motor rotor i8 a andageneratorarmature 24 having main brushes 9 2! (not shown in these views but which are shown in Figs. 5, 6 and 11) and close-circuited auxiliary brushes 2!, is positioned in rotatable relation therein by means of the bearings 23 and 4. Suitable means, such as the support member A I 23, may be secured to the under side of the frame ii to support themotor end thereof, and an end member may be secured to the frame ii at the'generator end, having a downwardly extended flanged portion 21 for supporting the generator end of the frame.

As illustrated in may be secured to the generator The end member 23 may be provided with a substantially flat outer face 23 and have, a boss 3| on the inner face,with a recess 3i thereinfor receiving the bearing 24, so as to support the genof the rotor member II. The motor m be suppor ed y in abearing housing integral part of the removable end of'the rotor member if 32, which is an I motor unit structure 12, the details of construction of which are clearly disclosed in the copendin: application of JohnH. 'Blankenbuehler and Theodore c- P'ockler, Serial No. 280,889, filed details of the generator June23, 1939. Further in the copending appli- R. Harding, Serial No. 280,688, filed June 23, 1939. In order to support the main brushes 2! and I the auxiliary brushes 2! in the p oper'operating only, and but a limited number of flux lines pass through the body portion of the field poles, the field pole members l4 and I! may comprise body members 40'an'd 4i, and separate arcuate shoe members 43 and 43. As only a limited number of maanetic flu: lines passthrough the'body members, they need not be laminated and may, be formed from solid blocks of soft section. The arcuato shoe members 42 and 43 are preferably laminated andof a substantial cross-section, so as to provide a relatively 'low reluctance path for a transverse crossdleld flux 1. of the drawings, the

. rivets 53 to provide an members in any suitable means ofbolts III, which tively large, suitable stay arcuate surfaces adjacent the armature 20 may be so arranged that the air gaps 41 at the leading edges thereof are smaller, and the air gaps 48 at the trailing edges are alike amount larger, than the normal value of'air gap used in machines of the crossefleld type.

The shoe members may be secured to the body manner, such as by pass through the frame II and the body members, and are threaded into the shoe members to secure'the shoe membersand the body members together, and to the frame. Inasmuch as the body members 40 and 4i are of relatively small cross-section, while the arcuateshoe'members 42 and 43 are reinprovided for bracing the pie, the stay members I field poles. For exammay comprise lengths of tubing of a non-magnetic material such as brass, or the like, used as spacers on bolts 52,

terial, and pass threaded into the through the frame and are shoe members.

As may be seen from magnetic shunt member 34 is positioned in bridged relation between the adjacent edges of the shoe members 42 and 43 for varying the output of the generator by varying the magnetic reluctance of the leakage path therebetween. The shunt member 54 may, for example, comprise a stack of similarly magnetic material secured together by means of elongated, channel-shaped member, with depending edge portions 51 and 33. which are disposed to. engage the substantially horizontal end surface portions 43 of the shoe members when the shunt member is in its lowest position. Suitable support means, such, for ex ample. as the projecting bearing members It may be secured to the sides of the shunt member 34 to provide for supporting the shunt member.

Referring to Figs. 1, 2, 9 and 10, it may be seen that guide members 33 and ii are provided for supporting the shunt member 64 in operating relation with the shoe members 33 and 3i in order to permit the widest range of variation in the magnetic reluctanceof the leakage path between the pole shoes, the guide members 3| and ii are preferably of a non-magnetic material such as brass and may comprise substantially flat plates thereof, adapted to be secured to the substantially vertical end surfaces 4' of the shoe members by means of screws 33.

surfaces edges thereof, on which the .members 53 on one side and a single one on the other, corresponding with the guide members, port for the shunt shunt member will the bearing surface of member. In this means r, the be stable in all positions. re-

gardless of variations in the alignment of the be notched at thetips to members 5i may be Piss. 1, 2, 7 and a, a-

shaped laminations 35 of to afford three points of sup-J bearing surfaces '3 within reasonable manufacturing tolerances.

In order to move the shunt member alon the bearing surfaces 63 of the guide members 80 and Bi and vary its position relative to the shoe members 42 and 43, suitable operating means may be provided, such for example. as the traveling nut member 64 which may be operatively connected to the shunt member 54 by means of a universal coupling member 8!. The traveling nut member 84 may be positioned on a threaded shaft 88 which is rotatably mounted in the frame H by a bearing block 81 attached to the interior of the frame, and a suitable bushing I in the end member 26, through which the shaft projects. The nut member 84 may be provided with an upstanding projection N which extends through a slot 10 in the frame H, for preventing rotation of the nut member, and indicating the output setting of the generator for each position of the shunt member on a suitable scale H which may be attached to the frame. Means such as the handwheel 12 may be provided for rotating the shaft 68 to effect movement of the nut member 54 therealong and vary the position of the shuntmember 84 relative to the shoe members, so as to alter the output of the generator.

By suitably shaping the bearing surfaces 63 of the guide members, and making them either plane or curved, as desired, the shunt member 84 may be caused to move along any desired predetermined path in response to actuation of the handwheel 12. As the shunt member is urged 'in the longitudinal or axial direction of the generator, by the traveling nut II, it will be apparmamas will be apparent that the flux designated by the ent from Fig. 1 that as the shunt member moves I to the right, from the position of minimum leakincreasing the reluctance of the leakage paththerebetween. In addition, as the shunt member 54 is moved to the right, the bearing members 58 which rest on the sloping hearing surfaces 83 of the guide members SI and II, will raise the shunt member so that instead of the depending edges 51 and 58 thereof resting on the horizontal edge portions 4! of the shoe members 42 and 43, they will be raised therefrom, thus additionally increasing the magnetic reluctance of the leakage path between the shoe members- Accordingly, will be apparent that a wider range of variation in the magnetic reluctance of the leakage path may be obtained by this arrangement of the shunt member, without requiring undue movement of the shunt member in any direction. Thus full advantage is taken of the limited space available within the frame of the generator for movement of the shunt member, without requiring complicated shunt operating mechanisms. As the surfaces ll on which the shunt member is supported are slidably engaged by the bearing members i! of the shunt member, and as the depending edges 51 and I. of the shunt member Y slidably engage the horizontal surface portion ll of the shoe members in the position of minimum reluctance as shown in Fig. 1, these sur-' dotted lines or in the body members ll and ll of the field poles must equal the sum of the excitation flux indicated by the dotted lines z traversing the armature 20 and the leakage flux indicated by the dotted-lines or. which passes through the shunt member 54. By adjusting the position of the shunt member 54 relative to the shoe members 42 and 43 the magnetic reluctance of the leakage path therebetween is varied, and the leakage flux or. is also varied. As the flux 4a is substantially constant throughout the operating range of the generator, because the restricted cross-section of the body members 40 and ll results in magnetic saturation thereof, any variation of the leakage flux 4n. will effect a change in the excitation flux s in the opposite sense. The circulating current i induced thereby in the auxiliary brush circuit of the generator armature 20 will be likewise varied,-and the cross-field or main flux u which is produced thereby, will be altered accordingly,

so as to change the voltage induced thereby between the main brushes 2| of the generator, thus varying the output of the generator.

Referring to Fig. 6 of the drawings, it may be seen that the shunt member 54 diverts relatively little flux from the armature under no load conditions, since the excitation flux ea passes into the armature from the lower portion of the pole shoes 42, and there is no tendency for it to pass through the shunt member. voltage of the generator is, therefore, retained at a relatively 'high value even at low output settings, thus facilitating the striking of the arc.- Under load conditions, the field windings i6 and I! increase the flux in the body members 42 and Q3 of the field poles so that it combines in part with the flux on, as shown in Fig. 5, and the shunt member 54 may be adjusted to shunt a large proportion of both of the said fluxes about the armature so as to control the excitation flux 4m: in the armature, and thus vary the voltage across the main brushes 2|, so as to control the output of the generator.'

In order to provide for controlling the terminal polarity of the cross-field welding generator, an auxiliary motor winding 86 is provided in coupled relation with the main stator winding 88 of the alternating current motor unit structure I2, and connected as illustrated in Fig. 11, to rectifying means, such as the bridge circuit 90 of unidirectional current devices 92, which may be conveniently mounted in the lower por-- tion of the frame ll, between the field poles id and'li, so as to provide a direct current polarity control potential whichmay be selectively applied to the field windings l8 and I! of the generator through the reversingswitch 94 to determine the polarity of the terminals thereof as desired. A suitableline' switch 95 may be provided for controlling the connection of the main motor windings 8.8 to a source of alternating current 91, having an operating winding 98 which is energized through a pushbutton switch 88.,

In order to provide a compact and efficient arrangement of the controls for readily controlling the operation of the motor-generator unit, the control switches for the motor and the generator may be mounted on the and member 25 in any suitable manner. The line switch 95 may, for example, be mounted directly on the outer face of the end member 28, in a manner such as cross-field generator embodying my invention, it 75 shown in Figs. 1, 3 and 4 of the drawings. The

control switch 94 and the pushbuttou switch 8! The open circuit are preferably also mounted on the and member adjacent the line switch, being, for example, suppo1 ted thereon by a bracket member H which is secured to the end member 25, so that the operating buttons 402, I03 and I04 thereof project through openings in a dished metal protective cover I06, which is secured to the end member in any suitable manner, as by means of screws I08 A similarly shaped cover H0 is preferably secured to the other end of the frame H, both covers being preferably of substantially the same diameter as the frame H, so as to harmonize therewith and conceal the control switches without requiring integral cast switch enclosures or expensive machining of the frame to position the control therein, and without rendering the control less accessible for inspection and repair. As the outer face of the end member 25 is substantially flat, and the flanged base 21 projects outwardly therefrom, by thus mounting the control switches, they are mounted substantially within the zone of support of the end member. Thus vibration and jarring of the control switches is reduced to a minimum, and their operation is rendered more reliable than when they are mounted on the frame of the set in an exposed position, and distant from a point of support of the motor-generator set so that the effect of shocks and vibrations on the control switches is magnified.

Since the field windings of a generator of the crossuicld type are normally connected in seriescircuit relationwith the main brushes and the load circuit, which comprises only the welding cables, the electrode, and the work, they are normally deenergized when the generator is running at no-load. The open circuit voltage across the main brushes of the cross-field generator is then dependent entirely on the residual magnetic flux in the field pole members, so that its terminal polarity may become reversed either because of the application of some external force, such as may result upon the connection of its welding electrode with the welding electrode of another generator having a. higheropen circuit voltage, or through an internal transient condition.

By applying a polarity controlling potential to the field windings l8 and I1 01' the generator through the reversing switch 94, in the manner hereinbefore explained, the residual magnetomotive force of the body members 40 and 41 of the field poles is increased, so that should the polarity of the reversal of the residual magnetic flux generator become reversed by a cident, it will be automatically returned to the Tect polarity by the polarity controlling potential, upon the removal of the external force, or the termination of the internal transient condition, thus maintaining the desired terminal polarity of the generator.

Referring to Fig. 6 of thedrawings, it may be seen that inasmuch as the auxiliary brushes 2| of the cross-field generator are close-circuited by the conductor H2, a circulating current iwill be induced in the auxiliary brush circuit when the generator is running under no-load conditions, by the residual magnetic flux or the excltation flux, which is represented by the dotted line 4m. Since the value of this circulating current under no-load conditions is directly dependent upon the residual magnetism of the field pole members, or the flux on, it will be apparent that the application of a polarity control potential to the field windings I6 and ll of the generator which will tend to increase the no-load value ficlent, and is easy to manufacture.

of the flux on, will correspondingly tend to increase the circulating current in the auxiliary brush armature circuit.

By providing the arcuate pole shoe members 42 and 43 with stepped arcuate portions adjacent the armature, so that the air gaps 41 at the leading portions of the pole shoes are increased, and the air gaps 48 at the trailing portions of the pole shoes are decreased, 2. like amount from the value of theuniform air gap normally used in a cross-field generator of this type, the tendency for any increase in the excitation fiux on, because of the polarity control excitation, is prevented. Since both of the air gaps 41 in the path oi the excitation flux Mare-increased, the magnetic reluctance of this flux path is increased, preventing any increase in the no-load value of the flux on, even though the no-load magnetomotive force acting on the field poles l4 and I5 is increased by the field windings l6 and I! of the generator being provided with auxiliary polarity controlling excitation. The harmful effects of an increase in the no-load circulating current in the auxiliary brush armature circuit arethereby avoided.

Since the voltage across the main brushes 2| of the generator is produced by the armature conductors cutting the cross-field flux, which is indicated by the dotted lines 4m, and which circulates through the arcuate. shoe members 42 and 43, and the flux on of each field pole includes in its path both the increased and the decreased air gaps 48 and 41 at the trailing and leading portions of the shoe members, respectively, no change in this flux is effected by this arrangement of air gaps, and, accordingly, the voltage across the main brushes 2! is unaifected.

From reference to the accompanying drawings and the above description, it will be apparent that by my invention I have provided a motorgenerator set or a generator of the cross-field type, wherein the output may be controlled in a simple and effective manner, and have provided a construction therefor that is compact and ef- The calibration of the output control is permanent and the control is protected from shock and vibration, and concealed from the eye so that the power unit has a pleasing appearance.

Since certain changes may be made in the above description, and diflerent. embodiments of the invention may be made without departing from the spirit thereof, it is intended that everything shown in the accompanying drawings and all matter contained in the above description shall be considered as illustrative, and not as alimitation.

I claim as my invention:

1. The combination with a generator comprising, a frame with oppositely positioned field pole members secured within the frame, of a slidable magnetic shunt member disposed to bridge ad- Jac'ent pole tips of the oppositely positioned field-pole members, adjusting means operable in the axial direction for effecting movement of the shunt member and indicating the output of the generator for different positions of the shunt member, and guide means positioned within the frame having bearing surfaces to support the shunt member so shaped as to guide it radially away from the pole tips as well as axially in response to operation of the adjusting means.

2. The combination in a generator, of a irame, a pair 01' oppositely disposed field-pole members positioned'within the frame, an armature rotatabiy positioned between the field-pole members, a slidable magnetic shunt member bridging adjacent pole tips of the oppositely disposed fieldpole members, a rotatable shaft member having a traveling nut member positioned thereon and operatively connected to the shunt member for eiiecting axial movement of the shunt member, and fixed guide means secured to the field-pole members having bearing surfaces so angularly related to the adjacent edges of the pole tips as to support the shunt member and direct it axially along and radially in a direction perpendicular to the pole tipsin response to operation of the adjusting means to provide a variable air gap between the magnetic shunt member and a part of the pole tips.

3. In a motor-generator set, the combination, of a unit frame, a plurality of generator field pole members having windings positioned within the frame in opposed relation adjacent one end thereof, a motor stator having a main winding secured within the other end of the unit frame, an auxiliary motor winding inductively coupledv with the main winding, circuit means connecting the auxiliary winding to one of the generator windings to control the no-load polarity of the fiux in the field pole members, a slidable magnetic shunt member for controlling the output of the generator supported by inclined guide members on adjacent pole tips of the opposed field pole members within the frame, means for operating the shunt member along the guide members to control the fiux in the field pole members and indicating the output of the generator, and control means controlling the energization of the main and auxiliary windings of the motor and the conmember in an axial direction relative to the armature and field pole members, and guide means slidably supporting the shunt member having surfaced portions so inclined to the longitudinal axis of the generator as to direct the shunt member radially away from the field pole members as well as axially of the armature in response to operation of the said means.

5. The combination with a generator having oppositely positioned field pole members with field windings and an armature rotatably supported therebetween, of a slidable magnetic shunt member positioned between the field pole members, operating means connected to the shunt member to move it relative to the field pole members along the axis of the armature, and fixed guide members secured to the field pole members slidably supporting the shunt member having bearing surfaces so shaped and inclined to the longitudinal axis of the armature as to effect movement of the shunt lmember radially nection oi the auxiliary motor and generator away from the field pole members as well as axially of the machine in response to operation of the operating means to provide air gaps between the shunt member and the field pole members which vary with the degree of overlap of the shunt member and field pole members.

6. The combination with a dynamo-electric machine having oppositely positioned field pole members with field windings positioned in a frame and an armature rotatably supported therebetween, of a movable shunt member positioned between adjoining tips of adjacent field pole members, control means operatively connected to the shunt member to urge it in an axialdirection between the field pole members, and guide members positioned within the frame having curved bearing surfaces for guiding the shunt member so inclined to the longitudinal axis of the generator. as to impart a predetermined radial movement to the shunt member away from the adjoining pole tips as well as axially in the direction of the longitudinal axis of the generator in response to operation of the control means.

Joan maximum-Ea. v 

